Intensity-invariant subpicosecond absorption saturation in heavy-ion irradiated bulk GaAs

Abstract
We demonstrate that bulk GaAs irradiated by heavy Au+ ions shows efficient saturable absorption with subpicosecond recovery time and without any relaxation rate saturation up to excitation densities as high as 1.6 mJ/cm2. A comparison with other types of ion irradiation shows that heavy-ion-irradiated GaAs is a very promising material for ultrafast optoelectronics and optical processing at high repetition rates.